A crusading Russian official traveled to Estonia in the summer of 2006 to warn the authorities that an unprecedented money-laundering scheme had been established in the tiny Baltic financial sector. The scam he had uncovered would go on to become the biggest dirty-money operation in history: the $200 billion Danske Bank scandal.

Three months after Andrei Kozlov, the first deputy chairman of the Russian Central Bank, tried to raise the alarm, he was dead.

Crooked beneficiaries of the illicit multibillion-dollar scheme to transfer money out of Russia included a member of Vladmir Putin's family and agents from the KGB's successor, the FSB, according to a leaked report drawn up by a bank insider.